Lithium

 

Lightest metal

Acts on Na+ channels but not exactly known

Blocks ADH too

Indications

  • Mood stabiliser / augmentation.

Dose 200-1000mgs nocte.

Monitoring

  • Check levels 12 hours after last dose.
  • Therapeutic window 0.4 to 1.0
  • Toxicity possible.
  • Always taper when stopping to avoid mood relapse.
  • Stick with same brand.

Interactions

  • NSAIDS
  • ACE-
  • SSRI ?
  • Diuretics

C/I in pregnancy  and avoid in pregnancy.

Very Common (>10% incidence) adverse effects of lithium include

  • Confusion
  • Constipation (usually transient, but can persist in some)
  • Decreased memory
  • Diarrhoea (usually transient, but can persist in some)
  • Dry mouth , metallic taste
  • ECG changes — usually benign changes in T waves.
  • Hand tremor (usually transient, but can persist in some)
  • Headache
  • Hyperreflexia — overresponsive reflexes.
  • Leucocytosis — elevated white blood cell count
  • Muscle weakness (usually transient, but can persist in some)
  • Myoclonus — muscle twitching.
  • Nausea (usually transient, but can persist in some)
  • Polydypsia — increased thirst.
  • Polyuria — increased urination.
  • Renal (kidney) toxicity which may lead to chronic kidney failure
  • Vomiting (usually transient, but can persist in some)
  • Vertigo
  • Weight gain

Common (1-10%) adverse effects include

  • Acne
  • Extrapyramidal side effects — movement-related problems such as muscle rigidity, parkinsonism, dystonia, etc.
  • Euthyroid goitre.
  • Hypothroidism
  • Hair loss/hair thinning

Hypothyroid x 6 times more likely in those on Li. Replace, do not change Li dose.

Toxicity s/s.

The manifestations include nausea, vomiting, diarrhoea, asthenia, ataxia, confusion, lethargy, polyuria, seizures, coarse tremor, muscle twitching, convulsions, coma and renal failure.

Overdosage, usually with plasma concentrations over 1.5 mmol Li per L may be fatal, and toxic effects include tremor, ataxia, dysarthria, nystagmus, renal impairment, confusion, and convulsions.


Diabetes insipidus

Hypothyroidism

Reduced renal function

Toxicity

Alternatives

  • Sodium valproate
  • Lamotrigine